Horizontal cylindrical furnace with removal of liquid slag



Dec. 12, 1967 v, GOLOVANOV' ET AL 3,357,383

HORIZONTAL CYLINDRICAL FURNACE WITH REMOVAL OF LIQUID SLAG Filed Aug. 5, 1965 United States Patent 3,357,383 HORIZONTAL CYLINDRICAL FURNACE WITH REMOVAL OF LIQUID SLAG Nikolai Vasilievich Golovanov, Gliuskaya, ulitsa, 1, kv.

39, and Viktor Vladimirovich Pomerantsev, Politekhnicheskaya ulitsa, 29, kv. 3, both of Leningrad, U.S.S.R.

Filed Aug. 5, 1965, Ser. No. 477,494 4 Claims. (Cl. 110-28) The present invention relates to horizontal cyclone furnaces for burning preferably a low-reaction pulverized fuel.

There are known horizontal and vertical cyclone furnaces of cylindrical shape with an axial supply of a finelyground fuel through a turbulent burner or with a tangential admittance of a pulverized fuel through uniflow burners, arranged along the generatrix of the furnace under the nozzles for secondary air tangentially admitted to the internal surface of the furnace.

In such furnaces the gases flow out in the axial direc tion through a conical or cylindrical branch pipe.

In said furnaces the fuel is burned under conditions of space turbulence where a film of liquid slag formed on the walls is likely to retain the coarse particles of fuel adhering to said film. Oxygen is supplied to these particles in a kinetic manner due to a great difference of velocities of particles being retained by the slag film and the air moving relatively to said particles.

The main disadvantages of said furnaces are an incomplete combustion of the fuel conditioned by the zone of a back flow of gases in the region of a gas-exit branch pipe, and a relatively high hydraulic pressure head.

There are also known cyclone furnaces for burning the pulverized fuel, the furnace chamber of which is both horizontal and cylindrical with a gas-exit port arranged longitudinally relative to the cylinder in the upper part thereof.

The fuel-supply nozzles are arranged at the gas-exit port and mounted tangentially in relation to a certain cylinder, disposed at a certain distance from the internal surface of the furnace.

Air is supplied in a dispersed manner through nozzles that are also mounted tangentially in relation to the above-said cylinder.

Such a supply of air causes an excessive cooling of the internal surface of the furnace and interferes with the formation of the film of liquid slag. The combustion of fuel occurs in the furnace chamber with the formation of a U-shaped flame and under conditions of the diffusion supply of oxygen to the fuel, the difference in velocities of particles of the fuel and air being insignificant.

Besides, in cyclone furnaces of said type it is impracticable to set up a multiple circulation of a fuel-air mixture, because the gas-exit port coincides with a tangent running through the port to the rotating flow counter to its direction.

The furnace according to the invention combines the advantages of said types of cyclone and turbulent furnaces and is free from the disadvantages inherent thereto.

An object of the present invention is the provision of a highly forced working furnace, the combustion of fuel in which is similar to the cyclone process.

Another object of the invention is the provision of a furnace having relatively small dimensions and a relatively small hydraulic pressure head.

A still further object of the present invention is the provision of a furnace which has no zone of back flow of gases at the gas-exit port.

Yet another object of the invention is the provision of a furnace, in which a multiple circulation of particles of 3,357,383 Patented Dec. 12, 1967 fuel, and consequently a more complete combustion of said fuel is provided.

According to the above-said and other objects, the present invention comprises a new device and a combination of parts and elements thereof as described hereinbelow and defined in the appended claims with the understanding, however, that modifications in the exact embodiment of the invention as disclosed herein may be made without departing from the spirit and scope of the invention.

Other objects and advantages of the present invention Will become more fully apparent from a consideration of the following description of an exemplary embodiment, taken in conjunction with the appended drawings, in which:

FIG. 1 is a cross-sectional view of a cyclone furnace provided with vertical burners;

FIG. 2 is a cross-sectional view of a cyclone furnace provided with horizontal burners.

The horizontal cylindrical furnace comprises curvilinear walls 1 made in the form of screens of pipes provided with pins, said pipes being lined with a refractory coating.

In the upper part of the furnace there is provided a gas-exit port 2 mounted longitudinally in relation to the cylinder.

The furnace is connected to a chamber 3 for cooling the boiler by means of a rectangular channel or a diffusor 4.

Portions 55 of the curvilinear internal surface of the furnace, adjoining the gas-exit port at the side of flow 6 of exit gases arriving at said port 2, has a smaller radius of curvature as compared with the remaining internal surface of the furnace so as to induce multiple circulation of the fuel-air mixture.

The fuel and air are supplied into the furnace through vertical or horizontal uniflow burners provided with a channel 7 for the mixture ofpulveri zed fuel and air and a channel 8 for the secondary air.

The burners, directed parallel to the tangent to the internal surface of the furnace, are arranged at the gasexit port, which provides a vigorous turbulence of the gas flow and sets up centrifugal forces therein.

Under the action of centrifugal forces, the particles of fuel at the outlet from the burners are directed to the periphery of the furnace, meeting on their Way a powerful current of the secondary air, issuing at a high velocity from the burners. As a result, there is brought about a thorough and uniform mixing of the fuel and air.

A portion of the circulating gas stream is simultaneously supplied to the mouth of the burners, said gas stream being heated to a high temperature which provides a rapid ignition of the fuel-air mixture.

Under the action of centrifugal forces, the ignited coarse particles of the fuel are expelled against the walls of the furnace covered with a film of liquid slag, and stick to said film.

The secondary air, reaching these particles at a high relative velocity provides conditions for their rapid combustion. The fine particles of the fuel burn in the furnace chamber, providing a rotating hot gas ring in its central part, which also contributes to the provision of a steady combustion of coarse particles of the fuel on the film of liquid slag and in the neighbourhood thereof.

The majority of the fuel particles burns completely before arriving at the gas-exit port. As to the particles burned incompletely, they, being influenced by the curvilinear area 5-5 with a smaller radius of curvature, become sharply deflected from the main gas flow, thus arriving together with a portion of hot gases into the primary Zone at which arrive the fuel and air. The curvilinear area 55 forms a protuberance as shown in FIGS. 1 and 2 which prevents tangential discharge of the exit gases through the exit port, Thereby a multiple circulation of incompletely burned particles and steady ignition of the fuel-air mixture are provided.

When the furnace operates under normal conditions, the temperature in it is maintained at a level considerably higher than the melting point of the fuel ash.

The presence of the hot surface in the furnace with the film of liquid slag contributes to the recovery of coagulated particles of ash from the rotating burning gas ring. The slag precipitates on the walls of the furnace chamber and drips off. Accumulated in the bottom part of the furnace, the slag drains through a tap 9, formed by the setting of pipes, into a slag receiver where it is granulated by means of cooling water or air.

Such a design of the furnace prevents the entrainment of coarse fuel and ash particles into the chamber for cooling the boiler with the main gas flow.

A relatively great multiplicity of circulation results in an increase ofthe time during which the particles remain in the furnace. This allows pulverized fuel with a small yield of volatile substances or with a great ash content to be burned in it with a relatively small consumption of energy for making the gas flow turbulent.

The furnace according to the invention allows a rapid combustion of other kinds of fuel, such as: high reaction coal and lignites, liquid fuel and gas.

There is no need of changing the shape of the furnace chamber; when burning liquid fuel and gas, there being modified only the channels for the pulverized fuel-air mixture, with the corresponding fuel-supply means placed thereinto.

Though the present invention is described in connection with the preferred embodiment, it is to be understood that alterations and modifications may be made therein without departing from the true idea and scope of the invention which will be readily understood by those skilled in the art. These alterations and modifications are considered as falling within the scope of the invention, as defined in the appended claims.

What we claim is:

1. A furnace with liquid slag removal adapted for burning low reaction pulverized fuel, said furnace com- 4. prising a hollow body having internal walls defining a cylindrical combustion chamber, means defining a gasexit port opening into the combustion chamber and extending longitudinally in relation to the cylindrical combustion chamber, and means disposed adjacent to said port for supplying fuel and air into the chamber tangentially along the internal wall'thereof, the latter means comprising a first channel for the discharge of fuel and.

air and a second channel for the discharge of secondary air, the channels being parallel to one another and immediately adjacent said exit port and disposed relative to the chamber such that the secondary air is discharged tangentially against the walls of the chamber and forms an outer layer for the fuel and air discharged from the first channel, said second channel constituting the sole source of secondary air for the furnace, the internal surface of the said body in the region of the exit port at the side thereof receiving the flow of exit gases having a smaller radius of curvature as compared with the remaining internal surface of the chamber and forming a protuberance for deflecting the gases and preventing tangential discharge thereof through the exit port.

2. A furnace as claimed in claim 1 wherein said exit port is vertical, said means for supplying fuel and air into the chamber comprising channels disposed substantially horizontally at the entrance of said exit port.

3. A furnace as claimed in claim 1 wherein said exit port is vertical, said means for supplying fuel and air into the chamber comprising channels disposed substantially vertically and immediately adjacent the exit port.

4. A furnace as claimed in claim 1 wherein said cylindrical combustion chamber is disposed along a horizontal axis and comprising a slag tap is provided at the bottom of the chamber substantially diametrically opposed to the exit port.

References Cited UNITED STATES PATENTS 2,654,350 10/1953 Fitzpatrick ll028 X 2,861,526 11/1958 Kuppers ll028 X CHARLES J. MYHRE, Primary Examiner. 

1. A FURNACE WITH LIQUID SLAG REMOVAL ADAPTED FOR BURNING LOW REATION PULVERIZED FUEL, SAID FURNACE COMPRISING A HOLLOW BODY HAVING INTERNL WALLS DEFINING A CYLINDRICAL COMBUSTION CHAMBER, MEANS DEFINING A GASEXIT PORT OPENING INTO THE COMBUSTION CHAMBER AND EXTENDING LONGITUDINALLY IN RELATION TO THE CYLINDRICAL COMBUSTION CHAMBER, AND MEANS DISPOSED ADJACENT TO SAID PORT FOR SUPPLYING FUEL AND AIR INTO THE CHAMBER TANGENTIALLY ALONG THE INTERNAL WALL THEREOF, THE LATTER MEANS COMPRISING A FIRST CHANNEL FOR THE DISCHARGE OF FUEL AND AIR AND A SECOND CHANNEL FOR THE DISCHARGE OF SECONDARY AIR, THE CHANNEL BEING PARALLEL TO ONE ANOTHER AND IMMEDIATELY ADJACENT SAID EXIT PORT AND DISPOSED RELATIVE TO 